First use your MacBook to format half the external drive in HFS+, then create an image to it with Time Machine.
(make certain the other half remains unformatted)
Then connect it to a PC and see if the other half of the drive can be recognized and formatted to NTFS through Windows Disk manager.

Thanks, good info.
I've never used that disk utility on the MAC, my wife's machine, just 30 years in the PC world.
The drive I'm looking at is a Seagate Backup Plus. It's a 3 TB single partition NTFS drive.
They give you a driver that will let the MAC read NTFS but won't work with Time Machine.
I was thinking I'd need to partition the drive into 2 on the PC then let the MAC reformat one partition to HFS+.
Would that work?
I guess it's 6 of one, half dozen...

Keep it simple if all you need to do with the drive is place images on it from the respective operating systems.
The more complexity you build into it the greater the chances of encountering issues.

To share data between the two you'll need a 3rd FAT32 partition, but you'll be confined to just 4GB data transfers/file sizes.
There are also paid for solutions, but you can do your own research into this.

Last edited by CLiNT; 2013-02-27 at 22:42.

DRIVE IMAGINGInvest a little time and energy in a well thought out BACKUP regimen and you will have minimal down time, and headache.